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CN-121994679-A - Method and system for detecting dynamic permeability of coal rock

CN121994679ACN 121994679 ACN121994679 ACN 121994679ACN-121994679-A

Abstract

The invention discloses a coal rock dynamic permeability detection method and system, which comprises the following steps of collecting seepage response data and executing pretreatment in a coal rock sample stress disturbance or loading evolution process, constructing a differential pressure sequence to generate a seepage response state set, constructing a seepage path node set, establishing a path connection relation set, calculating path transmission contribution values of all seepage paths to form a seepage path probability field, constructing a path topological structure matrix according to the seepage path probability field, calculating a path concentration index sequence, calculating a topological entropy sequence and a topological entropy change rate sequence, inputting the topological entropy sequence, the topological entropy change rate sequence and the path concentration index sequence into a permeability structure mapping model, and generating a coal rock dynamic permeability detection result. The invention adopts the path structure probability modeling method to realize the dynamic permeability detection of the coal rock, and has the advantages of strong structure sensitivity and high detection precision.

Inventors

  • CHEN XIAOBO
  • MENG FANLEI
  • LUO JIA
  • LIU WEI

Assignees

  • 鄂尔多斯市昊华精煤有限责任公司

Dates

Publication Date
20260508
Application Date
20260402

Claims (10)

  1. 1. The method for detecting the dynamic permeability of the coal rock is characterized by comprising the following steps of: Synchronously collecting seepage response data in the stress disturbance or loading evolution process of the coal rock sample, and performing pretreatment to generate a standardized seepage response data set; Constructing a differential pressure sequence based on the standardized seepage response data set, and establishing a one-to-one correspondence between the differential pressure sequence and the flow sequence under the same time index to generate a seepage response state set; constructing a seepage path node set according to the pressure difference distribution characteristic and the flow response delay characteristic in the seepage response state set, and constructing a path connection relation set according to the pressure difference transmission direction and the flow response delay relation to generate a seepage path candidate set; Calculating path transmission contribution values of all seepage paths based on differential pressure contribution proportion, flow ratio weight and time sequence stability index corresponding to all seepage paths in a seepage response state set, normalizing the path transmission contribution values to generate path transmission probability vectors, and binding the path transmission probability vectors with a seepage path candidate set to form a seepage path probability field; constructing a path topological structure matrix according to the seepage path probability field, and calculating a path concentration index sequence; Calculating a topological entropy sequence based on the path transmission probability vector and the path topological structure matrix, and calculating a topological entropy change rate sequence; Inputting the topological entropy sequence, the topological entropy change rate sequence and the path concentration index sequence into a permeability structure mapping model, generating a coal and rock dynamic permeability sequence, and outputting a coal and rock dynamic permeability detection result.
  2. 2. The method of claim 1, wherein the seepage response data comprises an inlet pore pressure sequence, an outlet pore pressure sequence and a flow sequence.
  3. 3. The method for detecting dynamic permeability of coal and rock according to claim 1, wherein the preprocessing comprises time index alignment, outlier rejection and amplitude normalization.
  4. 4. The method for detecting dynamic permeability of coal and rock according to claim 1, wherein the construction of the seepage response state set specifically comprises: based on the standardized seepage response data set, extracting a standardized inlet pore pressure sequence and a standardized outlet pore pressure sequence, calculating the difference between the standardized inlet pore pressure sequence and the standardized outlet pore pressure sequence point by point according to a uniform time index, and constructing a differential pressure sequence; Aligning and combining the differential pressure sequence and the standardized flow sequence according to the same time index to construct a combined data pair set containing differential pressure data and flow data; organizing the combined data pair sets according to the time index sequence to generate a seepage response state set; and performing index integrity check on the seepage response state set to obtain a seepage response state set with continuous and unique time indexes.
  5. 5. The method for detecting dynamic permeability of coal and rock according to claim 1, wherein the generation of the candidate set of seepage paths specifically comprises: Dividing the seepage response state set into continuous intervals to generate differential pressure transmission fragments, extracting a fragment average pressure difference value and a fragment differential pressure change rate from each differential pressure transmission fragment, and forming candidate node description data; Binding candidate node description data, flow response delay time and flow response duration time for each differential pressure transmission segment to form a seepage path node, and summarizing to obtain a seepage path node set; Performing connection judgment on the seepage path node set according to the pressure difference transmission direction and the flow response delay relation, and when the pressure difference transmission direction of adjacent seepage path nodes is kept continuous and the delay difference value is smaller than or equal to a preset flow response delay threshold value, establishing a connection edge between the corresponding nodes to generate a path connection relation set; and carrying out communication arrangement on the path connection relation set to generate a seepage path candidate set.
  6. 6. The method for detecting dynamic permeability of coal and rock according to claim 1, wherein the generation of the seepage path probability field specifically comprises: Sequentially acquiring a seepage path node sequence and a time index interval thereof corresponding to each candidate path in a seepage path candidate set, and extracting pressure difference data and flow data corresponding to each candidate path to form a candidate path response data set; generating differential pressure contribution ratios corresponding to each candidate path by taking the time index interval of each candidate path as a statistical range; generating flow duty ratio weights corresponding to each candidate path in the same time index interval; For each candidate path, sequentially reading the corresponding differential pressure data and flow data, calculating a differential value sequence of the differential pressure data and a differential value sequence of the flow data under adjacent time indexes, and calculating fluctuation discrete degree to obtain a time sequence stability index corresponding to each candidate path; the differential pressure contribution proportion, the flow duty ratio weight and the time sequence stability index corresponding to each candidate path are weighted and summed to obtain a path transmission contribution value corresponding to each candidate path, and a path transmission contribution value set is formed; normalizing the path transmission contribution value set to obtain path transmission probability values corresponding to each candidate path, and generating path transmission probability vectors according to the candidate path sequence in the seepage path candidate set; and respectively binding path transmission probability values corresponding to the candidate paths in the path transmission probability vectors to the corresponding candidate paths to generate a seepage path probability field.
  7. 7. The method for detecting dynamic permeability of coal and rock according to claim 1, wherein the generating of the path concentration index sequence specifically comprises: Sequentially reading all candidate paths in a seepage path probability field, extracting a starting point, an ending point, a starting time index, an ending time index and a path transmission probability value corresponding to each candidate path, and establishing a path index sequence; constructing a path topological structure matrix corresponding to the row index consistent with the column index by taking the total number of candidate paths in the path index sequence as a matrix dimension, and initializing all matrix elements to be zero values; Selecting a current candidate path as a current row corresponding path according to the path index sequence, reading the rest candidate paths one by one as current column corresponding paths, and extracting an ending point of the current row corresponding path, a starting point of the current column corresponding path, a termination time index of the current row corresponding path and a starting time index of the current column corresponding path; Generating a node connection judging value according to whether a connection edge relation exists between the ending point of the current line corresponding path and the starting point of the current column corresponding path, and generating a time connection judging value according to whether the starting time index of the current column corresponding path is positioned behind the ending time index of the current line corresponding path and whether the time index interval between the two is not more than a preset time connection threshold value; When the node connection judging value is satisfied and the time connection judging value is satisfied, writing a path transmission probability value of a path corresponding to the current column into a matrix element position corresponding to the current row index and the current column index to generate a path association value, and when the node connection judging value is unsatisfied or the time connection judging value is unsatisfied, keeping a corresponding matrix element to be a zero value; Sequentially writing matrix elements into all candidate paths in the path index sequence to obtain a path topology structure matrix containing path association values among the candidate paths, and determining matrix rows corresponding to each candidate path as a group of path association data; Counting the number of non-zero matrix elements according to each group of path association data to obtain a path association number value, accumulating all the non-zero matrix elements to obtain a path association total value, extracting a path transmission probability value of a path corresponding to the current line, weighting and summing the path transmission probability value, the path association number value and the path association total value to generate a path concentration index value corresponding to the current candidate path; and sequentially outputting path concentration index values corresponding to all the candidate paths according to the arrangement sequence of the path index sequences to generate a path concentration index sequence.
  8. 8. The method for detecting dynamic permeability of coal and rock according to claim 1, wherein the generation of the topological entropy change rate sequence specifically comprises: Reading the path topology structure matrix, extracting path association data corresponding to each matrix row and path transmission probability values of corresponding candidate paths, and taking all matrix elements in the current matrix row as topology distribution data corresponding to the current candidate paths; calculating a path association quantity value and a path association total value according to topology distribution data corresponding to the current candidate path; When the path association number value is greater than zero, respectively comparing each non-zero matrix element corresponding to the current candidate path with the path association total value to generate a topology distribution proportion set corresponding to the current candidate path, and when the path association number value is zero, marking the topology distribution proportion set corresponding to the current candidate path as a zero value set; the path transmission probability value is acted on each proportion value in the topological distribution proportion set corresponding to the current candidate path, and a probability weighting distribution value set corresponding to the current candidate path is obtained; sequentially performing logarithmic transformation and multiply-accumulate on each probability weighted distribution value in the probability weighted distribution value set to obtain a topological entropy value corresponding to the current candidate path, and marking the topological entropy value corresponding to the current candidate path as a zero value for the candidate path of which the topological distribution proportion set is a zero value set; sequentially writing the topological entropy values corresponding to all the candidate paths into a topological entropy result set according to the sequence of the path index sequence to obtain a topological entropy sequence, calculating a topological entropy change rate value and generating a topological entropy change rate sequence.
  9. 9. The method for detecting the dynamic permeability of the coal rock according to claim 1, wherein the generation of the dynamic permeability detection result of the coal rock specifically comprises: under the unified time index, aligning and normalizing the topological entropy sequence, the topological entropy change rate sequence and the path concentration index sequence, extracting normalized topological entropy, topological entropy change rate and path concentration index, and splicing to obtain a structure mapping vector sequence; inputting the structure mapping vector sequence into a permeability structure mapping model, and performing projection processing on each structure mapping vector in the permeability structure mapping model to obtain a structure characterization vector sequence with unified dimension; Carrying out component division on each structural characterization vector in the structural characterization vector sequence to obtain an entropy characterization component, an evolution characterization component and a centralized characterization component, carrying out cross mapping on the entropy characterization component and the evolution characterization component to generate structural evolution coupling characterization, and carrying out joint mapping on the structural evolution coupling characterization and the centralized characterization component to obtain a single-moment permeability candidate characterization vector; According to the time index sequence, recursively fusing the single-moment permeability candidate characterization vector corresponding to the current time index with the single-moment permeability candidate characterization vector corresponding to the previous time index to generate a permeability state vector sequence; Performing multi-layer perceptron mapping on the permeability state vector sequence to obtain a coal-rock dynamic permeability sequence; and binding the dynamic permeability sequence of the coal and the rock with the corresponding time index to form a dynamic permeability detection result of the coal and the rock.
  10. 10. A coal rock dynamic permeability detection system that performs the coal rock dynamic permeability detection method according to any one of claims 1 to 9, comprising: The data acquisition module is used for synchronously acquiring seepage response data in the stress disturbance or loading evolution process of the coal rock sample, and performing preprocessing to generate a standardized seepage response data set; The seepage response state construction module is used for constructing a differential pressure sequence and establishing a relation between the differential pressure sequence and the flow sequence to generate a seepage response state set; the seepage path candidate generation module is used for constructing a seepage path node set, establishing a path connection relation set according to the pressure difference transmission direction and the flow response delay relation, and generating a seepage path candidate set; the seepage path probability field construction module is used for calculating the path transmission contribution value of each seepage path, normalizing the path transmission contribution value, generating a path transmission probability vector and forming a seepage path probability field; The path topology analysis module is used for constructing a path topology structure matrix according to the seepage path probability field and calculating a path concentration index sequence; The topological entropy evolution module is used for calculating a topological entropy sequence based on the path transmission probability vector and the path topological structure matrix and calculating a topological entropy change rate sequence; The dynamic permeability generation module is used for inputting the topological entropy sequence, the topological entropy change rate sequence and the path concentration index sequence into the permeability structure mapping model, generating a coal-rock dynamic permeability sequence and outputting a coal-rock dynamic permeability detection result.

Description

Method and system for detecting dynamic permeability of coal rock Technical Field The invention relates to the field of coal rock seepage test, in particular to a method and a system for detecting dynamic permeability of coal rock. Background The permeability of the coal and rock is an important parameter for representing the fracture structure and fluid transmission capacity in the coal and rock medium, and is widely applied to the fields of coal bed gas development, groundwater seepage analysis and mine safety evaluation. In the prior art, dynamic permeability detection is generally based on Darcy's law, and a permeability value is obtained by inversion through measuring the functional relation between pressure difference and flow of inlet pore pressure, outlet pore pressure and flow data, or a step permeability result is obtained by fitting and analyzing pressure and flow time sequence data by a simple statistical method. However, the method mostly takes the direct functional relation of pressure difference and flow as a core, lacks the description of the permeation path structure reconstruction process and the channel concentration behavior, is difficult to reflect the dynamic change characteristics of the internal permeation structure of the coal rock in the stress disturbance or loading evolution process, and meanwhile, the traditional method usually ignores the influence of the pressure difference transmission direction, the flow response delay and the path communication relation on the permeation capacity evolution, so that the identification precision of the permeation rate change under the complex stress condition is insufficient, and the structural evolution rule of the permeation capacity of the coal rock is difficult to be accurately revealed. Disclosure of Invention The invention aims to provide a method and a system for detecting dynamic permeability of coal and rock, and the method and the system adopt a path structure probability modeling method to realize the detection of the dynamic permeability of the coal and rock and have the advantages of strong structural sensitivity and high detection precision. The method for detecting the dynamic permeability of the coal rock, provided by the embodiment of the invention, comprises the following steps of: Synchronously collecting seepage response data in the stress disturbance or loading evolution process of the coal rock sample, and performing pretreatment to generate a standardized seepage response data set; Constructing a differential pressure sequence based on the standardized seepage response data set, and establishing a one-to-one correspondence between the differential pressure sequence and the flow sequence under the same time index to generate a seepage response state set; constructing a seepage path node set according to the pressure difference distribution characteristic and the flow response delay characteristic in the seepage response state set, and constructing a path connection relation set according to the pressure difference transmission direction and the flow response delay relation to generate a seepage path candidate set; Calculating path transmission contribution values of all seepage paths based on differential pressure contribution proportion, flow ratio weight and time sequence stability index corresponding to all seepage paths in a seepage response state set, normalizing the path transmission contribution values to generate path transmission probability vectors, and binding the path transmission probability vectors with a seepage path candidate set to form a seepage path probability field; constructing a path topological structure matrix according to the seepage path probability field, and calculating a path concentration index sequence; Calculating a topological entropy sequence based on the path transmission probability vector and the path topological structure matrix, and calculating a topological entropy change rate sequence; Inputting the topological entropy sequence, the topological entropy change rate sequence and the path concentration index sequence into a permeability structure mapping model, generating a coal and rock dynamic permeability sequence, and outputting a coal and rock dynamic permeability detection result. Optionally, the percolation response data includes an inlet pore pressure sequence, an outlet pore pressure sequence, and a flow sequence. Optionally, the preprocessing includes time index alignment, outlier rejection and amplitude normalization. Optionally, the construction of the seepage response state set specifically includes: based on the standardized seepage response data set, extracting a standardized inlet pore pressure sequence and a standardized outlet pore pressure sequence, calculating the difference between the standardized inlet pore pressure sequence and the standardized outlet pore pressure sequence point by point according to a uniform time index, and constructing a differential pres